For me it is when companies/services market themselves as donating to XYZ cause if I buy their product. If they want to donate, they should have already done that with the money they have. Asking me to give them profit so that they can donate is so obviously pretentious.
Drive-by advertising. When someone joins a forum I’m active on just to let us know about their shiny new product and doesn’t participate in any other way. Even if it’s relevant, it’s still pretty scummy.